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Factors associated with leptospirosis in the district
Valsad, Gujarat, India, 2008
By
M. M. Lakhani
(FETP-MAE Scholar 2007-2008)
National Institute of Epidemiology
(Indian Council of Medical Research)
R-127, Tamil Nadu Housing Board Phase I and II, Chennai, 600 077
January 2009
Factors associated with leptospirosis in the district
Valsad, Gujarat, India, 2008.
by
M. M. Lakhani
(FETP-MAE Scholar 2007 -2008)
Dissertation project submitted in partial fulfillment of the requirements for the
degree of Master of Applied Epidemiology (M.A.E) of
Sree Chitra Tirunal Institute for Medical Sciences and
Technology,
Thiruvananthapuram, Kerala -695 011.
This work·has been done as part of the two years Field Epidemiology
Training Programme (FETP) conducted at
National Institute of Epidemiology,
(Indian Council of ~dical Research),
R-127, Tamil Nadu Housing Board Phase I and II,
Chennai, 600 077
January 2009
CERTIFICATION
This is to certify that this dissertation entitled ' Factors associated
with leptospirosis in the District Valsad, Gujarat, India, 2008 '
submitted by Dr. M. M. Lakhani in partial fulfillment J of the 0
requirements for the degree of Master of Applied Epidemiology is the
original work done by him and has not been submitted earlier in part . or whole for any other (Publication or degree) purpose.
Director,
National Institute of Epidemiology,
(ICMR), Chennai
Date:
ACKNOWLEDGEMENT
· Dignitaries of National Institute of Epidemiology and staff have helped me
in my dissertation work. I earnestly thank all of them.
Dr.Kumaraswamy, Officer in charge, NIE, guided and helped in ethical
clearance of the dissertation for MAE-FETP.
Dr. M.D. Gupte, Director (Retired), NIE, for providing an opportunity to .
undergo this course and for guidance, support and facilities for my works.
Dr. Yvan F. Hutin, WHO Resident advisor for the guidance and support
Dr.R.Ramakrishnan, Deputy Director, NIE, Chennai and my mentor for
constant guidance for all of my project reports. He guided me personally at
NIE and also at my field posting in Valsad, Gujarat. Dr. Manoj Murhekar,
Deputy Director, NIE, course co-coordinator guided me and took care of
me all the time. Dr.Vidya Ramachandran, Dr.Sunder Murthy, Dr. P.
Manickam, Dr.Jabbar, Dr.Josheph and several scientists and. staff of NIE,
Chennai for their help in my work. Mr. Satish, Librarian and Mrs. Uma
Manoharan, Secretary to FETP facilitated my work.
I am very grateful to all dignitaries of my Gujarat state and Valsad district
for their support in my study. I earnestly thank all of them.
Dr. Amarjit Singh, Commissioner, Health, Medical Services and Medical
education (Health, Med. S ·and Med. Edu.), Gujarat for selecting and
deputing me for this course. He supported me for field projects.
Madam Mona Khandhar, Joint Secretary (Health, Med. Sand Med. Edu.)
for all administrative supports for deputation.
4
Mr. N.A. Vora, District Development Officer, Valsad made it possible to
<)
clear all necessary administrative works for deputation in time. He always
guided and facilitated my work in field postings at Valsad.
Dr. Vikas Desai, Additional Director (FW) has been my teacher and guide
for more than a decade. She has been an inspiring source for my work.
Dr.Pandya, Add. Dir. Dr. S.J. Gandhi, Dy. Dir, Epi. Ceii,Dr.Panchal,
Gandhi nagar for all his support in my project works.
Dr.M.K.Gajera, Chief District Health Officer, Valsad always helped me in
carrying out my studies in Valsad. He facilitated my work by providing
facilities in office and field areas. His advice and suggestions helped me a
lot to improve my work. Dr.Trivedi, HOD of Medicine; Dr.Somaiya Mulla,
HOD of Microbiology; Dr.Godara, Asst. Prof. PSM, Govt. Medical College,
Surat, Dr.B.K.Panchal, RCHO, Valsad, Dr.Vaidya, COHO, Ahmedabad,
Dr.Kulkarni, Dr.Tejas of Municipal corporation , Ahmedabad for their help
in my MAE-FETP works. All block health officers, medical officers and
staff of health department, Valsad for the support in my all project works.
All my family members for providing me encouragement and comfort to
work. My father encouraged me to complete my study in spite of his
illness. My two cute nieces miss Alisha and Muskan for their help.
Date: 31 /12/2008 Dr. M. M. Lakhani
Place: Chennai
5
' I CONTENTS
Section 1: Dissertation Page No.
Abstract
1. Introduction ....................................................................... 9
2. Methods .......................................................................... 12
3. Results ................................................................ 17
4. Discussion ........................................................................ 18
5. Conclusion ..................... : ....................................... 22
6. References ........................................................... 23
7. Figures .................................................................. 27
8 Tables .................................................................... 29
9. Annexure I Informed consent form ............................ 35
10. Annexure II Identifier collection sheet ......................... 38
11. Annexure Ill Data collection instrument: questionnaire ... 39
Section II: Review of literature
1. Introduction ........................................................... 43
2. Historical aspects .................................................... 44
3. Public health importance .......................................... .44
4. Epidemiology .......................................................... 46
5. Risk factors of leptospirosis ....................................... 51.
6. Review of s~udies for risk factors ................................ 55
7. Prevention·and control ............................................. 62
8. Summary ............................................................... 65
9. References .................................................. ; .......... 66
SECTION: I 0
0
DISSERTATION
ABSTRACT
Background: Leptospirosis is endemic in Valsad since 1994. Average
incidence is 3.5 per 1.00.000 popl:.llation and case fatality 17.5 %. 1.6 million
people are at ris~. The disease incidence, case fatality increased in spite of
preventive measures. We did the study with objectives of 1. To study factors
associated with leptospirosis in Valsad. 2. Formulate recommendations.
Methods~
We did a prospective, matched case-control study in Valsad district, Gujarat
during June to October, 2008. We defined a leptospirosis case as a disease
with (1) >20 score in the WHO clinical assessment scale and (2) Titre > 1:80
in MAT or > 1 :40 in ELISA lgM or four fold rising titre in paired serum
sample by ELISA or PCR positive. We searched cases by active and
passive surveillance. We recruited three controls per case at random from
the same village matched for ~ge group ( +/- 5 year) and sex. The sample ,
size was 44 cases and 132 controls. We collected information about general
characteristics, potential exposures, and personal protective and hygienic
practices using a pre-tested structured questionnaire. We did matched odds
ratio and conditional logistic regression analysis of exposure factors.
Results: 7 4 suspected leptospirosis cases occurred in Valsad with incidence
rate 4.46 per 1, 00,000 population and case fatality ratio 26 %. Highest and
lowest incidence was 6 and 1 per 1, 00,000 in Valsad and Kaparada Taluka,
respectively. The age group 45-59 years was affected most. No case was
reported in 0-5 year age-group. Males were affected more but case fatality
was eqaal. 1 0 factors were significantly associated with leptospirosis.
Conditional multivariate logistic regression a·nalysis indicated house
compound wet(OR 16.28, 95% Cl 3.12-84.91) and cuts/wounds on limbs(OR
8.92, 95% Cl2.37-33.53) as independent risk factors.
Conclusions: House compound wet and having cuts/wounds on limb are
risk factors of leptospirosis in Valsad.
Factors associated with leptospirosis in the district of Valsad, Gujarat, India, 2008
Dr.M. M. Lakhani, MAE-FETP Scholar, VII Cohort, NIE (ICMR), Chennai, 27 Dec, 2008 Mentor: l;)r. R. Ramakrishnan, Deputy Director, NIE (ICMR), Chennai, Tamilnadu, India.
1. Introduction:
Leptospirosis is an acute zoonotic disease caused by infection with
spirochetes belonging to the genus leptospira 1• 2. Clinically, it is
characterized by fever, headache, myalgia, conjunctival suffusion, jaundice,
breathlessness or oliguria. Main complications are renal, hepatic, pulmonary,
haematological, brain and cardiac1· 2. Leptospirosis has high epidemic
potential and the case fatality can be 05-40 %1. Rodents and animals are
carrier of the disease. The urine of rodents, animals and dogs contains
leptospira which contaminates the environmene· 4• 5 Hence, leptospirosis is a
potential occupational health hazards for those working in close proximity of
such environment. The contaminated soil becomes source of infection for
human beings. Heavy rain, wet and warm environment provides favorable
environment for survival of leptospira5. Hence, Agricultural laborers, animal
handlers, forest workers, sewage workers and outdoor workers who work in
wet condition are at higher risk of leptospirosis.· Cuts or wounds on limbs are
known risk factors of the disease5-8 Leptospirae can also be transmitted
through mucosal surfaces, abrasions in skin, through the conjunctiva or by
inhalation into lung of droplets containing leptospires 1
The incidence of leptospirosis is very high in tropical and subtropical
countries. It ranged from 18-128 per 100,000 in Barbados9 and 40-60 6per
100,000 in Seychelles5· Globally an average of 10,000 severe cases
requiring hospitalization occurs annually all over the world 10. Almost every
country in South and Southeast Asia, South and Central America and
several Island nations across the world are endemic to leptospirosis.
Leptospirosis outbreaks have occurred in Seychelle~ (Indian Ocean) 5 ,
Nicaragua 11 , Argentina 12, Brazil13. Thailand14, Colombia 15, Guana 16,
Japan17,Mexico18, Bangladesh19, Vietnam20, Cubana21 and lndia22•23 . The
incidence is increasing in developed countries.
In South East Asia Region, it is endemic disease as the economies of these
countries are predominantly agriculturai and more than 922 million people
are engaged in agriculture. Rice is th~ major food grain cultivated in this
region. Most of these countries have heavy rainfall resulting in water logging
which predispose to occurrence of leptospirosis24. It affects reproductive
group of people causing enormous economic loss 10.
In India epidemics have occurred in Andaman lslands25, Gujarat26,
Maharastra27, Kerala28, Tamilnadu29 and Orissa30. In Gujarat Valsad,
Navsari and Surat are districts endemic for leptospirosis26 .1360 villages
were affected in the 3 districts of south Gujarat region during 1994-2004.
The case fatality was 7.6% in 1994 with a peak of 22.5% in 1996. Average
case fatality was 11.4 ~/o in this region 10•26.
In Valsad, leptospirosis cases occurred first time in 1994. 1.66 million people
· are at risk in Valsad district. Our field project of secondary data analysis
indicated that during 2000-2006 the average incidence was 3.5 per 1 ,00,000
population and the case fatality 11.5 %. The highest incidence rate was 5
per 1 ,00,000 in the age group of 15-44 years. As compared to 2006, in 2007
the incidence rate increased from 2.5 to 6.38 per 1 ,00,000 population and
the case fatality increased from 17.5 to 24 %31 . Leptospirosis control
programme was launched in 1996. Under the leptospirosis control
programme of Gujarat health departmene1, activities were done for ( 1)
Information, education and communication (IEC) to increase awareness C)
about leptospirosis disease (2) Daily house to house active surveillance by 0
health workers during monsoon for earl~ case detection and treatment of
suspected cases (3) Weekly chemoprophylaxis with Cap. Doxycycline to the
agricultural laborers in highly affected villages ( 4) Presumptive treatment of
all cases of fever in high risk population with two capsule of doxycycline for
seven days (5) Arrangement for prompt referral of the patients to higher
treatment cent~e (6) Management of cuts, abrasions and treatment of the
cases (7) Rodent control by pesticides during the month of May. Moreover,
government of Gujarat had launched special campaign of cleanliness in
Gujarat named as "Nirmal Gujarat"
The persistence of the disease and increase in the incidence and case
fatality in spite of control measures emphasized the need for a studl2 . The
information generated by this study will allow more effective prevention and
control measures in the district as well as similar areas of Gujarat state with
the disease. We did the study with following objectives of 1. To study factors
associated with leptospirosis in Valsad district, Gujarat, 2008. 2. Formulate
recommendations for prevention and control of leptospirosis.
2. Methods
Study population
The study population was permanent resident of Valsad district, Gujarat,
India, 2008. The calculated midyear 2008 population of Valsad district was
16,60,00033 . The characteristics of the area are plain fertile land, average
rainfall of 200 ems per year and hot and humid climate. 73 % of the total
population is rural. 70 % of rural population is engaged in agriculture work.
Rice, sugarcane are main crops34. lhese factors are favorable for
transmission of leptospirosis. Hence, the study population is relevant to 0
answer the research question.
Study design
We conducted a prospective matched case control study during monsoost
period of June to October, 2008.
Inclusion criteria: We included cases of leptospirosis confirmed by
laboratory tests, as per case definition.
Exclusion ··criteria: We excluded all suspected cases that were not
confirmed or who died before laboratory confirmation. We excluded malaria
patient positive by blood smear examination. We also excluded cases
belonging to other district.
Case definition
A leptospirosis case was defined as a disease with (1) >20 score in the
WHO clinical assessll)ent scale 1 and (2) PCR positive or Seroconversion for
serology by Microscopic Agglutination Test (MAT) titre>80 or ELISA titer >40
in one serum sample or four fold rising antibody titre in paired sera taken 14
days apart 35•36
Sampling procedure:
We searched for symptomatic cases by house to house active surveillance
with help of multipurpose health workers of health department, in all the 470
villages of Valsad. We also searched cases by passive surveillance at
primary health centre (PHC), community health centre(CHC) and all major
hospitals of the Valsad district during June to October, 2008. The medical
officer suspected case of leptospirosis, the block health officer verified and
assigned a unique line listing number (LL No.) to the case-patient. We
interviewed case-patients having > 20 score as per WHO scoring form 1• 47
of the total 74 suspected cases were laboratory confirmed. We removed 3
cases randomly from the list and and recruited 44 cases for our study.
We selected persons as controls who were free from any signs/symptoms of
leptospirosis for the last 30odays of onset of the disease in the case, We
included controls, prospectively who were residing in the village at least for
the last one year. To recruit controls, we selected a house in the
neighborhood of the case-patient by using last number of any currency note
taken randomly. A healthy person matching age (+/- 5 years) and sex was
taken as first control. In the similar way, we recruited second and third
control randomly. We recruited three age-sex matched controls for each
case. Thus, we recruited 132 controls for the 44 cases. We followed the
controls prospectively for period of 30 days to rule out occurrence of
disease. No control had any sign/symptom of leptospirosis, during that
period.
Sample size
We used Epi info 3.3.2 statcal, software to calculate sample size. The
sample size was estimated for a power of 80%, an alpha error of 5% and a
frequency of ex~osure of risk factor (agriculture population) among controls
70 % to detect an odds ratio of 3 with three controls per case. So, our
• sample size was 44 leptospirosis cases and 132 controls. We interviewed
1 0 % more cases and controls for non-response.
e Data collection: We designed data collection instruments as semi-
structured questionnaire. We translated the data collection instruments in the
local language Gujarati and back translated in English. We pilot tested the
data collection instruments in the field before actual study and made
necessary changes. We trained medical officers and health staff during May,
2008. We collected the data with help of trained health staff using personal
interview, observation of premises and review of medical and laboratory
records. We collected information from cases and controls about general
characteristics, demographic, socioeconomic characteristics, occupational
exposure, cuts and abrasions, hygiene and health seeking behavior practice.
Staff of agriculture and veterinary department helped in collecting
information about animals and rodents population. The health supervisors
supervised the health workers.
Laboratory specimen collection, transport and analysis
The multipurpose health worker/supervisor skilled in blood sample taking or
laboratory technician collected first blood sample from the clinically
suspected case of leptospirosis. We tested the specimens at microbiology
department of government medical college, Surat, Gujarat. We collected
14
paired sera sample from the same patient after 14 days and tested in the
similar way.
Data analysis:
Data entry: We used Epi info software version 3.3.2. Trained data entry
operators entered data under our guidance. Two different persons had
entered and re-entered the data and compared for the correctness.
Descriptive epidemiology:
We calculated incidence rate of leptospirosis by dividing total number of the
suspected leptospirosis cases with population under study. We plotted the
cases by week of onset to get epi-curve to know time trend. We calculated
age-sex specific and blockwise attack rates. We plotted on a map
geographical distribution of cases.
Analytical epidemiology:
We measured the frequency of exposures to specific factors among cases )
and controls. We calculated matched Odds ratio. ·with 95 % confidence
interval and p value to measure the strength of the association of the factors
with leptospirosis. We did stratified analysis of risk factors to detect and
minimize confounder and effect modifiers. We also did multivariate logistiq
regression analysis for the factors found significant in univariate analysis to
find independent risk factors of leptospirosis.
Quality assurance
We developed protocol, submitted for peer review before the faculty and
other MAE-FETP Scholars and revised. We sought. clearance from ethical
committee of National Institute of Epidemiology (NIE), Indian Council of
Medical Research, Chennai. The principle investigator cross checked 10%
15
•
of the participant interviews. The block health officers and medical officers
cross check 20% of the field works. We followed standard laboratory
methods and 'procedures for collection, transportation and testing of
specimens. The head of the department of microbiology, government
medical college, Surat, Gujarat supervised for quality assurance.
Human subject protection
We could not find any leptospirosis case in vulnerable population of
pregnant 'NOmen or children. We followed the ethical guideline of Indian
Council of Medical Research for human subject protection.
Risks
We interviewed patients without disturbing treatment schedule. We
considered comfort and convenience of the participants. This laboratory
investigation was a part of routine investigation for the treatment of the
disease. We used a new syringe and needle to take blood samples and
took all universal aseptic and antiseptic precautions. There was no adverse
event due to the questionnaire or taking specimen. We managed the
interviews with the help of the medical officers. We followed the ethical
guidelines for testing of blood samples.
Benefits
The case-patients benefited for early diagnosis and treatment. We educated
the controls for the disease. No compensation was given for participation in
the study and this was informe'd to the participants before taking consent.
16
Confidentiality
To protect the confidentiality of study subject we used only an identifier code.
We kept it under lock and key and destroyed after Jhe project. We ensured
privacy of the participants during an interview ..
Informed consent
We explained the participants the objectives of the study in their local
language Gujarati. We told them their rights and obtained written informed
consent in presence of a witness.
Ethical committee clearance
We sought approval of study protocol the ethical committee of National
Institute of Epidemiology (ICMR), Chennai, Tamilnadu, India.
3. Result:
Total 74 cases of suspectedleptospirosis occurred in Valsad during June to .,.
October, 2008. The first case occurred on 7th June with peak in 2nct .week of
august and last case on 6th October, 2008. All over incidence rate was 4.46
per 1, 00,000 population. All the 5 blocks of Valsad district were affected.
Highest and lowest incidence was 6 and 1 per 1, 00,000 in Valsad and
Kaparada Taluka, respectively. All over case fatality of suspected cases of
leptospirosis was 26 %. The age group 45-59 years was affected most with
attack rate 16.87 per 1, 00,000 and cases fatality of 32 %. No case was
reported in 0-5 year age group. Males were affected more than females with
attack rate 6.37 against 2.38 per 1, 00,000 population. Sexwise case fatality
was almost equal (25 % against 26 %). The cases were tested for
leptocheck rapid test, ELISA, MAT and PCR. 47 (64%) of the 74 cases were
17
0
r I I II
positive by at least one laboratory test. 32 (73%) cases were positive by
ELISA and 27(61%) by MAT or PCR. The types of serovars found were L.
icterohaemorrhagiae, L. canico/a, L.grippotyphosa, L.automonalis, L.
pyrogen. L.hebdo L. australis, and L. Pomona
We included 44 laboratory confirmed cases in our study. 24(55%) cases had
liver and kidney involvement,14 (32%) cases had lung involvement (Table
2). All the 44 cases(100%) had fever followed by myalgia 33(75%),
headache (66%), jaundice (48%) and conjunctival suffusion (32%). 31(70%)
cases had contact possible contaminated water. 34(77%) cases had
exposure to agriculture work.
'The matched case control study indicated 1 0 factors as significantly
associated with leptospirosis. ~n stratified analysis, association of house
compound wet and leptospirosis was stronger amongst persons having rats
at home (OR 9.94, 95% Cl 3.60-27.46, P 0.0000) as compare to not having
rats.
Conditional multivariate logistic regression analysis of all above significant
factors identified two factors, house compound wet (OR 16.28, 95% Cl 3.12-
84.91, P 0.001) and cuts or wounds on limbs (OR 8.92, 95% Cl 2.37-33.53,
P .0012) as independent risk factors of leptospirosis.
4. Discussion:
Total 74 cases of suspected leptospirosis occurred in Valsad during June to
October, 2008 with i'lcidence rate 4.46 per 1 ,00,000 population which is
comparatively less than other tropical countries5·6·7(Figure 1 ). All the five
blocks of Valsad district were affected (Figure 2). The case fatality of was 26
%. Incidence and case fatality was highest in of 45-59 year age group 10· 26.
18
Higher age group was affected in Valsad as compared to previous years26 .
Leptospirosis is known to affect male productive group of people . Males
were affected almost three times more than females but case fatality was 0
almost equal (Table 1 ). Liver and kidney involvement was more followed by
lung involvement (Table 2). All the cases had fever. Other main
signs/symptoms were myalgia, headache, jaundice and conjunctival
suffusion (Table2). Agriculture workers were highest affected followed by
other laborer.
We recruited 44 laboratory confirmed cases for analytical study. The
analysis indicated factors that affected the risk of leptospirosis in Valsad
district of Gujarat. Living in Kaccha house, illness in animals in house, rats
at home, contact of contaminated water, agriculture work, outdoor
occupation, swimming/bathing in river, house compound wet and having cuts
or wounds on limbs were risk factors for leptospirosis. In further conditional
logistic regression multivariate analysis, two of the factors were found
significant. The first was related to condition of house premise and the
second to hygienic and protective practices. A review of these results
provides some understanding of the practices that expose the community to
leptospirosis and provide useful direction to suggest behavior change
interventions for prevention.
House compound wet and having cuts or wounds on limbs were strongly
associated with leptospirosis in Valsad. The exposure to cuts or wounds on
limbs was nine times higher and house compound wet was sixteen times
higher in cases than controls. Other studies in different area indicated that
walking on wet land was associated with leptospirosis 1,4·5·8. Cuts or wounds
19
owere reported as risk factors "0f leptospirosis in other studies done in
Seychelles (Indian Ocean), Hawaii islands and Thailand5•6•7•8• Thus, our
study is consistent with other studies.
Wet land provides environment to leptospirae organisms to grow
effectively 1•5 . The wet compound of houses may be contaminated by urine of
cattle or rats in rural area 1·3.4·5 . In our study, the stratified analysis indicated
that the association between house compound wet and leptospirosis was
stronger amongst persons having rat at home. In rural area of Valsad distlict,
large proportion of houses are made of mud. The house compound remains
wet due to rain and practices of people to discard waste water nearby
houses. Cut or wounds on limbs are common in rural people and people
have tendency to ignore them. This makes them vulnerable to leptospirosis.
Cuts or abrasions in skin facilitates the entry of leptospires.1, Hence, the
biological correlation also supports the result of our study.
Our study suggests that there may be opportunities to prevent leptospirosis
through addressing the sources of infection. These include house compound
wet and having cuts or wounds on limbs. To reduce incidence a number of
interventions need to take place. First, we need to advocate community for
·keeping house compound dry and clean, prevent unsanitary environment in
the surrounding of houses, creating awareness by campaign of " Nirmal
Gujarat" and doing minor engineering works in the house compound to
prevent stagnation of. water. Second, we need to promote hygienic and
protective practices amongst the community for preventing cuts or wounds
on limbs. Educate people regarding the risk of leptospirosis associated with
,having cuts or wounds on limbs and motivate them to wear footwear to
20
protect. We need to promote health seeking behavior of people to take early
treatment for cuts or wound on the limbs. Educate them to minimize
exposures to risk factors of leptospirosis while having cuts or wounds.
Ill Further studies could characterize the strength of association of leptospirosis
with environment sanitation of housings and types, severity and duration of
cuts and wounds. Finally, public health surveillance will provide an
opportunity to evaluate the effectiveness of the proposed prevention,
promotion and curative measures.
Limitation:
The regular health staff of health care system collected the data which might
have caused selection and information bias. We minimized the probable bias
by following random selection of controls using last digit of a currency note.
The specificity of ELISA and MAT tests is 90 %. This could have lead to
misclassification of cases. To minimize it we used case definition combining
clinical and laboratory criteria. The patients were aware of their diagnosis at
the time of interview which could result in bias leading to overestimation of
strength of association. To overcome the bias we combined interview with
observation of the environment for risk factors. The study was done in the
restricted area of Valsad district. Epidemiology of leptospirosis may differ in
other places. Hence, the risk factors may not be similar elsewhere. Findings
can not be generalized to larger population, but can be generalize to similar
areas having similar environment, socioeconomic and cultural habits. We did
not test serum of controls to rule out leptospirosis infection, as our object
was to study clinical cases and not prevalence of infection. To rule out
misclassification of controls, we followed them for 30 clays of incubation
21
period. We did not find any sign/symptoms of leptospiro~is in controls during
follow up period. We studied during monsoon period of June to October,
2008. Hence, the study might have failed to identify risk factors resulting
from other seasonal activities. As such, cases were reported only in
monsoon season in Valsad since 199426. So, it is less likely to have other
seasonal risk factors. We did not include water sports as risk factor in our
study as they are not found in study area.
Conclusion:
House compound wet and having cuts or wounds on limb are risk factors of
leptospirosis in Valsad district, Gujarat, India.
Recommendations:
We recommend creating awareness in the community regarding risk of
leptospirosis associated with house compound wet and having cuts and
wounds on limbs. Educate people for keeping house compound dry to
protect them. Improve housing to ensure that house compound does not
remain wet. The village Panchayat can take measures to prevent stagnation
of water nearby houses during rainy season. Promote hygienic and
protective practices amongst people for cleanliness of limbs and wearing
footwear to prevent cuts and wounds on limbs. Promote health seeking
behavior in the community for treatment of cuts and wounds. Educate people
to minimize exposures to risk factors of leptospirosis while having cuts and
wounds on limbs.
22 -- --------~--------~---~---
0
References:
1. Faine S. 1982, Guideline for control of leptospirosis. Geneva, WHO.
2. Levett PN. Leptospirosis, Clin. Microbial Rev 2001; 14:296-326
3. Vintez JM, Leptospirosis, Curr Opin Infect Dis 2001 ; 14 :527-38
4. Ferguson IR. Human leptospirosis. The state veterinary journal·
(Ministry of Agriculture, Fisheries and Food) 1990;44: 131-44)
5. Pascal Bovet, Claude Yersin, Fabrice Merien, Clarence E Davis, Philippe
Parolat, Factors associated with,clinicalleptospirosis: A Population-based
case control study in the Seychelles(lndian Ocean), Int. J Epi
1999;28:583-590
6. Sasaki DM, Pang L, Minette HP et al, Active surveillance and risk factors
for leptospirosis in Hawaii. Am. J Trop Med. Hyg. 1993;48:35-43
7. Sugunan AP, Natrajaseenivasan K Vijayachari P Sehgal SC, "
Percutaneous exposure resulting in laboratory- aquired leptospirosis-a
case report, J Med Microbial, 2005 Sept;54(Pt 9):907.
8. TangKanakul, Risk factors associated with leptospirosis in North-East
Thailand, 1998,
9. Douglin CP, Jordan C, Rock R, Hurley A, Levett PN, Risk factors of 0 -
severe leptospirosis in the parish of St. Andrew, Barbados, Emerg Infect
Dis. 1997 Jan-March;3( 1 ):78-80.
10. Souvenir, 5th Annual congress of Indian leptospirosis Society, Surat,
Gujarat. Supported.by Govt. of Gujarat, WHO & ICMR , 20th -22nd
January, 2005
23
11. CDC. Outbreak of acute febrile illness and pulmonary haemorrhage
Nicaragua, 1995. MMWR 1995;44:841-3
12. Vanasco NB, et al, A study for Clinical characteristics and risk factors of
human leptospirosis in Argentina. Acta Trop. 2008 Jul 12.
13 Lacerda HG, et al, Leptospirosis in a subsistence farming community in
Brazil. Trans R Soc Trop Med Hyg. 2008 Jul 1. [Epub ahead of print]
14. Surveillance of leptospirosis after flooding at Loei Province, Thailand by
year 2002. Southeast Asian J Trop Med Public Health. 2005
15. Leptospirosis in Uraba, Antioquia, Colombia: a seroepidemiological and
risk factor survey in the urban population. Cad Saude Publica. 2007
Sep;23(9):2094-1 02.
16. Liverpool J, et al, Leptospirosis: case reports of an outbreak in Guyana,
USA Ann Trop Med Parasitol, 2008 Apr; 1 02(3):239-45.
17. Kawaguchi L, et al, Seroprevalence of leptospirosis and risk factor
analysis in flood-prone rural areas in Lao PDR, Japan. Am J Trop Med
Hyg. 2008 Jun;78(6):957-61.
18. Risk factors and the prevalence of leptospirosis infection in a rural
community of Chiapas, Mexico. Epidemiollnfect. 2003
19. Seroprevalence of leptospirosis in a rural flood prone district of
Bangladesh. Epidemiollnfect. 1994
20. Human leptospirosis in the Mekong delta, Viet Nam. Trans R Soc Trop
Med Hyg.1998
21. HernAindez MS, et al, Outbreaks of animal and human leptospirosis in
the province of Ciego de Avila. Rev Cubana Med Trop. 2005 Jan
Apr;57(1 ):79-80.
24
22. Leptospirosis in India. WHO/OMS, 1998 Disease outbreaks reported, 27
October 1997.
23. John T J. Emerging and reemerging bacterial pathogens in India. Indian
J. Med. Res. 1996;103:4-18.
24. John T J. The prevention and control of human leptospirosis. J. Post
grad. Med. 2005;51 :205-9
25. Vijayachari P, Sugunan AP, Sharma S, Roy S, Natarajaseenivasan K,
Sehgal SC. Leptospirosis in the Andaman Islands, India. Trans R Soc
Trop Med Hyg. 2008 Feb;102(2):117-22.
26. Patel BK, Gandhi SJ, Desai DC. Clinico-epidemiological aspect of
leptospirosis in South Gujarat, Indian J Med Microbiol, 2006 [cited 2008
Apr 7]; 24: 322-5.
27. A De,A Varaiya, A Pujari, M Mathur, M Bhatt, S Karande, ME Yeolekar,
An outbreak of leptospirosis in Mumbai. Ind. J. Med Micro (2002) 20 (3):
153-155
28. Kuriakose M, Eapen CK, Paul R.Leptospirosis in Kolenchery, Kerala,
India: epidemiology, prevalent local serogroups and serovars and a new
serovar. Eur J Epidemiol. 1997 Sep; 13(6):691-7.
29. Muthusethupathi MA, Shivakumar S, Suguna R, Jayakumar M,
Vijayakumar R, Everard CO, Carrington DG. Leptospirosis in Madras--a
clinical and serological study, J Assoc Physicians India. 1995 Jul; 43(7):
456-8
30. Sehgal SC, Sugunan AP, Vijayachari P. Outbreak of leptospirosis after
the cyclone in Orissa. Nat/ Med J India. 2002
25
31. Commissionerate, health, medical services, medical education(HS),
action plan for leptospirosis prevention and control, 1996-2008.
32. Reports on leptospirosis,2000-2007, Health branch, District Panchayat,
Valsad, Gujarat, India.
33. Census report, Gujarat, India, 2001. 0
34. Data from annual diary, District Panchayat, Valsad, Gujarat, India, 2008.
35. Sumaiya M.,Godara N. Guideline on confirmation of leptospirosis, Dept.
of Microbiology and Community Medicine, Government Medical college, o
Surat, Gujarat, 2008.
36. Pamer MF Lab. Diagnosis M~d.Lab. Sci 1988;45:174-78
26
Figure 21ncidence of suspected cases of leptospirosis by blocks, Valsad, Gujara1, lnd,ia, 2008
Kapraia
D
Leptospirosis incidence per 1.00.000
• >3 ·1-3 0<1
iililllllfrll !ilr•~•1n •••nrs· t,
28
Table 1: Incidence of suspected cases of leptospirosis by age and sex,
Valsad, Gujarat, India, 2008 Demographic Cases Death 2008 Attack rate Case fatality characteristics population per 100,000 ratio(0/o)
Age < 5' 0 0 215800 0 0 0
group 6-14 1 1 398400 0.26 100 (Years)
15-44 35 7 763600 4.58 20 "
45-59 28 9 166000 16.87 32
60+ 10 2 116200 8.6 20
Sex Male 55 14 863200 6.37 25
Female 19 5 796800 2.38 26
Total 74 19 16,60,000 4.46 26
29 Q
..
Table 2: Characteristics of leptospirosis cases, Valsad, Gujarat, India, 2008 (n=44)
Characteristics # (o/o)
Severity Without complication 14 32
With complication 30 68
Organ involvement Liver 24 55
Kidney 24 55
Haematological 23 52 Lung 14 32
Cardiac 0 0 Brain 0 0
Clinical description Fever 44 100 Myalgia 33 75 Headache 29 66
"' Jaundice 21 48 Oliguria 16 36 Conjunctival suffusion 14 32 Bleeding. 3 7 Breathlessness 3 7 Cough 0 3 7 Meningism
0
0 0 Other. characteristics Contact contaminated water 31 70 Laboratory results MAT Positive 27 61
ELISA Positive: Single high titre 32 73 ELISA Paired sera rising titre 23 52 PCR Positive 27 61
'"' 30
.•
h..
Table 3: Frequency of baseline characteristics among leptospirosis cases and controls, Valsad, Gujarat, India, 2008. { cases=44, controls=132)
1. Baseline characteristics Cases % Controls % Chi Sq. p
Age >20 years 44 100 132 100 0 1
Sex Male sex 33 75 99 75 0 1
Living area Rural 41 93 123 93 0.12 1
Caste ST/SC/OBC 44 100 11~ 90 3.35 0.04
Education Illiterate 16 36 36 27 1.31 0.25
Income Monthly lncome<1200 21 48 42 32 3.63 0.056
31
Table 4: Univariate matched odds ratios, confidence intervals of potential exposures in leptospirosis cases and controls, Valsad, Gujarat, India, 2008 ..
Cases{44}, Control{132} Concordant Discordant Matched
Exposure within 30 days of onset I interview for exposure status for exposure status) OR 95%CI Exposed Unexposed Exposed Unexposed M-H
1. Baseline characteristics Caste ST/SC 99 6 24 3 8 1.28-49.86
Education Illiterate 17 65 31 19 1.63 0.73-3.61
Income Monthly lncome<1200 28 55 35 14 2.5 1.07-5.8
2. Living environment
House in low-lying land 0 128 Status of house
3 1 3 0.19-47.96
House compound wet 52 6 65 9 7.22 2.76-18.92
Type of house Kachcha house 58 26 35 13 2.69 1.1-6.58
Any animal 49 38 26 19 1.37 0.59-3.16
Cattle 33 51 33 15 2.2 0.94-5.17
Animals in house Goats 6 101 12 13 0.92 0.30-2.81
Dogs 3 118 6 5 1.2 0.29-6.31
Illness in animals Any illness noted 0 108 21 3 7 1.59-30.80
Exposure to rodents At home 96 5 27 4 6.75 1.40-32.66
At work place 52 41 26 13 Q 2 0.78-5.16
Stream 0 132 0 0 0 0
Water source for Well 12 97 9 14 0.64 0.19-2.17 drinking Hand pump 65 29 22 16 1.37 0.54-3.48
Tap 19 96 8 9 0.89 0.23-3.46
32
Table 4 Continues ... Characteristics Match 95%C\
Exposed Unexposed Exposed Unexposed OR
Stream 2 128 1 1 1 0.02-50.40
Water source for Well 14 90 16 12 1.33 0.47-3.76
washing Hand pump 64 32 20 16 1.25 0.49-3.2
Tap 12 100 6 14 0.42 0.10-1.78
Cow dunk/urine in yard 27 53 33 19 1.74 0.80-3.78 Peri-domestic 0
environment Animals in the yard 35 52 22 23 0.96 0.42-2.19
Pigs around house 3 123 6 0 undefined
Contact Contact contam. water 37 26 56 13 4.31 1.84-10.10
With animals 13 81 26 12 2.17 0.85-5.52
Milking cattle 6 99 12 15 0.8 0.27-2.38 Activities Working
On a farm 48 19 52 11 4.91 1.97-12.26
Occupation outdoor 104 8 16 4 4 0.78-20.50
Wash/bath after work 122 3 4 3 0.133 0.16-11; 14
Swim in stream/river 3 96 30 3 10.00 2.67-37.42
Walk barefooted 119 3 4 6 0.67 0.12-3.78 Hygiene and
Poarch cleaned 51 32 24 25 0.96 0.43-2.12 protective practices
Cuts/wounds on limbs 9 47 69 7 9.86 4.09-23.74
Medicine taken 8 82 19 23 0.83 0.35-1.97
Antibiotic taken 2 105 7 18 0.39 0.11-1.39
33
Table 5 Conditional logistic regression of significant exposures of leptospirosis, Valsad, Gujarat, India, 2008.
Exposures in 30 days Odds Ratio 95% C.l. P-Value
House compound wet 16.278 3.12-84.91 0.00
Rats at home 9.8628 0.90-108.36 0.06
Cuts-wounds on limbs 8.923 2.37-33.53 0.00
Swim/bath in river/stream 3.9504 0.60-26.17 0.15
Agriculture work done u 3.2561 0.55-19.13 0.19
Contact contaminated Water 1.9921 0.50-8.00 0.33
Monthly income<1200 1.4313 0.34-5.95 0.62
Handle animals 1.3761 0.30-6.41 0.68
"' Animal ill in house 0.9991 0.06-17.32 1.00 "
Cow/ox in house 0.1754 0.026-1.16 0.07
34
•
ANNEXURE: 1
Consent form for study on factors associated with leptospirosis in
the district Valsad of Gujarat, India, 2008
Hello,
lam and am working with the
health department, district panchayat, Valsad to look into factors that may
put you at risk for leptospirosis or protect you from them. We are9 doing
this research as a response to more than hundred cases of leptospirosis
in Valsad between June and October in the year 2007. The National
Institute of Epidemiology, Chennai is also working with us.
To find out factors associated with leptospirosis disease, we need to ask
questions about the ~isk -factors for the disease to persons who had
leptospirosis and to healthy persons. Thus, between June 08 and October . 2008, we will be asking the same questions to some of the persons with
leptospirosis, as well as to some healthy members of the area. We would
like to confidentially ask these few questions to you once. Answering
these questions should take about 30 minutes of your time.
For cases only: For this study, we will go to your village and ask the same
questions we asked you to three of your neighbors. However, we will not
mention any medical information about you and we will not mention that
we have come and see them because there was a case of disease in their
area. We would like, to make a few blood tests and take 5 ml or one tea
spoonfuls of blood on two occasions, at intervals of fourteen days. We will
use a new, single use syringes and needle and follow standard hygiene
rules. You may experience only a slight pain during collection of the blood
35
sample. These tests are also part of the regular medical care that you
need. They will be sent for testing at the microbiology department,
Government medical college, Surat, Gujarat. The blood will. be tested for
leptospirosis only and nothing else. Any leftover blood will be discarded.
Taking part in this survey is voluntary. No compensation will be paid to
you for taking part in this study. You can choose not to take part. You can
choose not to answer a specific question. You can also stop answering
these questions at any time without having to provide a reason. This will
not affect your rights to health care in the primary health centre,
community health centre/referral hospital, Civil Hospital, Valsad, or any ,
other rights. There is no specific benefit for you if you take part in the
survey. However, taking part in the survey may be of benefit to the
community, as it may help us to understandothe problem, its causes and
potential solutions. When the results will have been analyzed, a report will
be shared with all the participants and the local health officials concerned
with public health, so that the right measures can be taken to prevent and
control leptospirosis in Valsad as well as Gujarat.
The information we will collect in this survey will remain between you and
the health department. We may ask questions about various specific
things you do. This does not mean that we think that these things you do
would put you at risk for leptospirosis. It does not mean either that we
think that these things you do would protect you from leptospirosis either.
We will not write your name on this form. We will only use a code instead.
Only the doctor will know the key to this code. It will be kept under lock
and key. It will be destroyed after the project.
36
If you wish to find out more about this survey before taking part, you can
ask me all the questions you want. You can contact Dr.M.M.Lakhani, 0
MAE-FETP Scholar (VIIth Cohort) and principal investigator of this survey
attached to the National Institute of Epidemiology, Chennai, at the health
branch, Valsad or chief district health officer attached to the health
branch, Valsad, who will be happy to give you more details. If you are OK
to take part, we will go ahead now.
I have read the foregoing information, or it has been read to me. I have
had the opportunity to ask questions about it and any questions I have
asked have been answered to my satisfaction. -I consent voluntarily to
participate as a participant in this study and understand that I have the
right to withdraw from the study at any time without in any way it affecting
my further medical care.
Name of the study participant or Signature/thumb impression
guardian (if minor) of the study participant or
guardian
Name of the witness Signature of the witness
Name of the interviewer Signature of the interviewer
37
Annexure 2
Identifier collection sheet
Personal identifier segment
Status of participant: Case/Control Date of the interview:
., Name of participant: _________________ _
Primary health center's name: __________ _
Name of sub centre: -------
Name of the village: _________ _
Age in complete years: __ years
Gender: 1 . Male 2. Female
Religion: 1. Hindu 2. Muslim 3. Christian 4. Others
Caste: 1. General 2. ST 3. S04. Other backward caste (OBC)
0
Participant's identifier code: I I· ·I I I I I
First box is for district Valsad (V), second for the block, third for rural (R) or
urban (U); four to six are for numbers of the volunteer. The Block codes are
given below:
Valsad Pardi Umergaon Dharampur Kaparada
Codes Va Pa Urn Dh K
38
Annexure 3
Data collection instrument items for inclusion in the questionnaire I structured observation guide, Date of interview:
Leptospirosrs study, Valsad, Gujarat, India, 2008.
Participant's Identifier Code · I I I I I I I
• What is your age? !Years
• What is the respondent's sex? 1. Male 2. Female
• What is your religion 1. Hinduism 12. Muslim
3. Christianity 4. Other
• What is your caste? 1. General 2. Scheduled tribe
3. Schedule caste 4. backward caste
• Type of residence 1. Urban . 2. Rural
• Level of house 1. Average 2. low lying
• Type of house 1. Kaccha (made 2. Pakka (made of -
pf mud wood) brick and cement)
• What is your occupation? 1. Animal herding 12. Farming
3. Other labour 4. Trade
5. Home maker 6. Teaching
7. Office work 8. Student
9. Unemployed 9. Other
• Could you tell me what is your Rupees
monthly average family income ?
• Up to what level have taken 0. No education 1.<=7 std.
education? 12. 8-12 std 14.>=graduate
• Do you have animals in the house? 1. Yes 2. No·
• If yes, which animals are there ? 1. Cow/ox 12.Buffelo
3. Goat 4.Dog
5. Cat
• How many animals do you have? 1.<5 12.>=5
• Was any animal ill within 30 days . 1.Yes 12.No
prior to the onset of symptoms/ before?
39
• How frequently did you see rodents 0. Never 1 . Occasionally
in I around your house within 30 days ( 1-3 times a week)
prior to the onset of symptoms/ before? 2. Often 3. Daily
(>3 times a week) "'
• How frequently did you see rodents 0. Never 1.0ccasionally
in your areas of activity within 30 days ( 1-3 times a week)
prior to the onset of symptoms/ 30 days 2. Often 3. Daily
before? (>3 times a week)
• Do you rear animals in the yard ? 1. Yes 2.No
• If. yes, how many: A-nimals ~
• Is there cow dunk-urine in the yard ? 1.Yes 2.No
• How often do you find pigs around 0. Never 1 . Occasionally
your house? ( 1-3 times a week)
12. Often 3. Daily
(> 3 times a week)
• Did you have contact of dirty water 1. Yes 12.No
within 30 days prior to the onset of
symptoms/30days before?
• Did you handle animal in 30 days 1. Yes 2.No
prior to the onset of symptoms/ before?
• Did you do agriculture work within 1. Yes 2.No
30 days prior to the onset of symptoms/
before?
• Were you involved in milking of 1. Yes 2.No
cattle within 30 days of onset of
symptoms/30days before? . • Did your house compound remain 1. Yes [2.No
wet within 30 days prior to the onset of
symptoms/30days before?
• How frequently did you pass across 0. Never 1 . Occasionally ( 1-
wet land within 30 days prior to the onset 3 times a week)
of symptoms/30days before? 2. Often 3. Daily
(>3 times a week)
40
• From where do you get water for 1. Stream 2.Well
drinking? 3. Hand pump 14.Tap
• From where do you get water for 1. Stream ~.Well
drinking? 3. Hand pump 14. Tap
• How frequently did you suffer from 0. Never 1. Occasionally
cuts/wounds within 30 days prior to the (1-3 times a week)
onset of symptoms/30days before? 2. Often 3. Daily
) (>3 times a week)
• If suffered, did you take treatment 1. Yes 2.No
for cuts/wounds within 30 days prior to
the onset of symptoms/30days before?
• How many times did you wash 0. Never 1. Occasionally
yourself/bathe after the daily activities (1-3 times a week)
within 30 days prior to the onset of ~.Often 3. Daily
symptoms/30days before? (>3 times a week)
• How many times did you swim in a 0. Never 1. Occasionally
stream within 30 days prior to the onset (1-3 times a week)
of symptoms/30days before?· 2. Often 3. Daily
(>3 times a week)
• How frequently did you use tools to 0. Never 1 . Occasionally
clean premise within 30 days prior to the (1-3 times a week)
onset of symptoms/30days before? 2. Often 3. Daily
{>3 times a week)
• Did you take any medicine within 30 1. Yes l2.No
days prior to the onset of the symptoms/
in 30 days?
• If yes, mention the details (Verify the
prescription/bills)
Signature ofthe interviewer
41
SECTION: 2
LITERATURE REVIEW
42
Section II: Review of literature: Leptospirosis
1. lntroducfion
Leptospirosis is an acute bacterial infeCtion caused by spirochetes
belonging to family leptospiraceae 1·2·3.4·5. It is a zoonosis of worldwide
distribution, endemic mainly in countries with humid subtropical or tropical
climates and has epidemic potential6. Heavy rain, hot and humid
environm~nt favors the survival of the leptospires organisms 1·2•3•10 1n the
developed world, most cases are associated with recreational exposure to
contaminated wate~·7•9 . The incidence is increasing in developing
countries. It is an occupational hazard in the south east Asia region
(SEARO) for the people working in the agriculture, animal herding, forest
and sewer cleaning, abattoir , mine works8 . Thailand, where leptospirosis
is under surveillance, has recorded increase in incidence 17 . The
incidence of leptospirosis is very high in tropical and subtropical countries.
It ranged from 18-128 per 100,000 in Barbados18 .In a study the incidence
of leptospirosis in Seychelles was found 40-60 per 1 00,00010· On an
average 10,000 severe cases requiring hospitalization occur annually all
over the world 19 Outbreaks have been reported in other countries of
Nicaragua20, Argentina21 and Brazil22 • Thailand23, Colombia24, Guana25,
Japan26,Mexico27, Bangladesh28, Vietnam29, Cubana30 and lndia31 •32
Leptospirosis is emerging disease in lndia32 . In India epidemics have
occurred in Andaman lslands34, Gujarae5, Maharastra36, Kerala37,
Tamilnadu38 and Orissa39. Some of these were as a result of natural
calamities such as post cyclone outbreak in Orissa39 and post flood in
Mumbai36.
43
In Gujarat Valsad, Navsari and Surat are districts endemic for
leptospirosis23•35 .1360 villages were affected in the 3 districts of south
Gujarat region during 1994-2004. The case fatality was 7.6 % in 1994 with
a peak of 22.5 % in 1996. Average case fatality was 11.4 % in this
region23• In Valsad, leptospirosis cases occurred first time in 1994. 1.66
million people are at risk in Valsad district. Our field project of secondary
data analysis indicated that during 2000-2006 the average incidence was
3.5 per 1 ,00,000 population and the case fatality 11.5 %.
Historical aspects
Stimson demonstrated the first one of leptospira (Abdussalam M et a/,
1965) which was subsequently confirmed by WHO research fellows doing
work on leptospirosis during 1962-65. Faine S. has mentioned about
similar occupational hazard of farmers in china
Public health importance
Leptospirosis is worldwide public health problem (World Health
Organization, 2003). Leptospirosis affects productive group of people
which cause great socioeconomic impact. It has high case fatality ratio of
5-40% (Singh SS eta/, 1999).Leptospirosis accounts for about 12.7% of
cases of acute febrile illness attending Hospitals in India (Sehgal SC et a/,
2003). In Thailand, .the annual incidence of leptospirosis increased from
0.3/100,000 to 3.3/100,000 population during the period 1982 - 1995 to
1997 - 9817. Sehgal SC et a/ (1995) reported leptospires as the
aetiological agents in Andaman Haemorrhagic Fever (AHF) in North
44
Andaman in 1993. Zaki SR & Sheih WJ (1996) also reported that
leptospires was the aetiology of the acute febrile illness with pulmonary
haemorrhage in Nicaragua in 1995. Ko AI et a/ (1999) reported
leptospirosis outbreaks in urban Salvador in Brazil through a hospital
based surveillance system where the case fatality rate was 15%. In a
study following the super-cyclone in Orissa in 1999, 14% of the study
subjects had febrile illness due to leptospiral infection (Sehgal SC et a/
(WHO, 2001 ). A study by Karende S et a/(2002) in Mumbai during heavy
rainfall and floods in July- August 2001, 30 (32%) th'e 93 children having
suspected leptospirosis were confirmed for leptospirosis based on rapid
diagnostic tests. A seroprevalence in North Andaman was of 54% among
apparently healthy population (Murhekar MV et a/, 1998). The study also
indicated seroprevalence more than 72% in older adults. High
seroprevalence was observed among some of the primitive tribes of
Andaman and Nicobar Districts (Sehgal SC eta/, 1999a).
Ratnam Set a/(1983) studied the seroprevalence among the people of a
village near Chennai City following an outbreak of leptospirosis in cattle.
47% of the participants showed antibodies against leptospires. In a study
conducted Vado-solis I et a/, 2002 in Yucatan State of Mexico 57
(14.25%) of the 400 participants were found positive for leptospires. A
study in Seychelles (Bovet P et a/, 1999) showed 9% point prevalence of
assymptomatic leptospiral infection as proved by positive PCR. (Sehgal
SC eta/, 2000a)reported 27% seropositivity in Andaman Island.
45
Q,
Epidemiology of leptospirosis:
Agent factors:
Pathogenic leptospires are the agent of leptospirosis which belong
to the genus Leptospira. They are long corkscrew-shaped bacteria, too
thin to be visible under the ordinary microscope. The organism leptospira
is tightly coiled, thin spirochete measuring 5-7 micron. The end is bent
into a hook 11 . They are motile by a flagellar action2 . They are Gram
negative. There are 25 groups and 200 serovars of leptospira5 . WHO
reports more than 240 pathogenic serovars3 . Genus leptospira consist of
two spieces L. interogan and L.Biflexa. The former is pathogenic strain.
Other leptospires recognized include L. icterohaemorrhagiae, L. canicola,
L.grippotyphosa, L. Valsada, L. australis, L. bataviae, L. tarassovi and L.
. Pomona. Rodents and cattle are carrier that sheds leptospira in urine for
years. Leptospira can survive for long periods in water and wet soil. Some
serovars of leptospires are known to survive in soil for up to 7 4 days and
can grow, multiply and retain their infective potential2·3.
Hosts: Leptospirosis affects most of vertebrate animals. Rodents, cattle,
dogs, cats and wild animals are main hosts. From animals the disease is
transmitted to human8 .
Factors in human
Age: Leptospirosis affects the productive age groups of people due to
their exposures to outdoor occupations.
Sex: Males are affected more due to more exposure to outdoor
occupation.
Caste: Lower socioeconomic people are affected more.
46
Occupation: Agriculture workers, animal handlers, abattoirs, sewer J
workers, fisherman and outdoor laborer working in close proximity of
contaminated environment by leptospira are affected most.
Housings: Mud thatched house is found to be a risk factor.
!)
Environmental factors: Hot, humid or wet environment favor growth of
leptospirosis 10. Heavy rain and water lodgment is good media for
leptospires. Hence the disease has high incidence in such areas33 .
Salinity of soil: Alkaline type soil favors growth of leptospires3 PH of 7.00
to 7.4 is favorable for growth.
Source of infection: Contaminated environment by leptospires, water
bodies, soil are source of infection of leptospirosis.
Modes of transmission: The transmission of the disease can be direct or
indirect. Direct transmission in animals occurs by haematogenous, by
suckling milk from infected mother, by sexual _transmission or Tran
placental. Ellis WA et a/1986 reported that by this mode, leptospires enter
new host from body fluid or urine of infected animal or body fluid. Direct
transmission is common in butchers, veterinarians, cattle, pig handlers
and rodent control workers. Bolin CA and Koellner P indicated in 1988
the possibility of. human-to-human transmission through breast-feeding. ·
Indirect transmission of leptospirosis occurs through contaminated
environment by urine of infected animals. Cuts and abrasions in skin
facilitate entry of leptospira(Faine S).2 Leptospira can also enter the host
through intact skin 11 . The leptospira are also transmitted through skin
lesions and mucus membranes of mouth, pharynx, and esophagus by
ingestion of food and drink contaminated by the urine of the reservoir
47
animal12 . Leptospirosis has been recognized as a potential hazard of
water sports and other recreational activities. Ingestion of contaminated
water was reported to cause leptospirosis by Corwin A et a/ in 1990. He
who investigated an outbreak of leptospirosis at Okinawa, Japan and
reported that swallowing water while swimming was significantly
0
associated with leptospirosis. The incubation usually lasts about 10 days
(2 to 30 days)3.4.
Clinical features:
The clinically leptospirosis is characterized by mainly two forms. The
icteric form represents with jaundice. Other signs/symptoms includes
fever, headache, conjunctival suffusion 1·2·3·13 •
The complications include myocarditis, acute meningitis, renal failure,
• pulmonary filtration, haemorrhage, hepatic involvement, iridocyclitis.
Vinetz JM, reported pulmonary haemorrhage as the complication of . leptospirosis from china7. Acute Respiratory Failure was studied by Silvia
RRV & Brauner JS in 2002. Myocarditis was reported by Ramachandran
S & Perera MVF in 1977. Uveitis is also a complication of leptospirosis 12.
In south Gujarat area the complications included involvement of kidney,
liver, lung, haematological, cardiac and brain 13 . Renal involvements are
very common in leptpospirosis42
Clinical diagnosis:
As per WHO guideline for leptospirosis Faine, scoring of more than 20 in
scoring scale indicates suspected case of leptospirosis. In south Gujarat a
suspected case of leptospirosis was considered when a case of fever had
48
any two of the symptoms namely1. Myalgia2. Conjunctival suffusion and
3. Agriculture worker or a person with history of contact with animals35.
Laboratory diagnosis:
Diagnostic tests for leptospirosis are Rapid test, ELISA, MAT, PCR,
immunofluroscent Tests, Dark field illumination microscopic test, Isolation
of leptospiras and cultures. Leptospirae can be detected from Blood,
urine, CSF. ELISA serological test can detect leptospirosis as early as 3
days in acute stage. A titre of >40 in· single test has diagnostic value.
Four fold rise in the titre is considered as diagnostic2 . The sensitivity and
specificity of the test is 93%. Microscopic agglutination test (MAT} is done
using live battery of leptospira. Cut point for minimum titre for diagnosis is
1:80.
Polymerase chain reaction array test can detect antigen of leptospirosis .. as early as 3 days. Leptospiras can be detected in urine after 2nd week of
infection. Other investigations include renal, hepatic function and
haematological blood tests. High level of Serum transaminase in "
leptospirosis cases is useful in differentiating it from hepatitis 13. Serum
urea, creatinine are increased in renal involvement. Serum urea more
than 40/dl of blood is significant. The platelet count below 60,000 per
.,1 OOml blood can lead to haemorrhagic manifestations 13
Differential diagnosis:
In tropical and tem.perate countries the important diseases should be
differentiated from leptospirosis. These include malaria, dengue, viral
fever, yellow fever, enteric fever, scrub typhus and hanta virus fever.
49
Treatment:
Due to rapid complications leading to high case fatality early detection
and treatment can save life. The Leptospirosis Information Center on
website recommends the treatment as follows: Severe infections should
be managed with IV benzyl penicillin and will require hospital admission.
Adult dose is 5MU to 8MU per day for five days although in some studies
the doses have been routinely very much higher - up to 20MU. There is
no evidence that doses over 8MU have an additional benefit, but doses
below 5MU may be inadequate. Other authors also recommend penicillin
as drug of choice. Benzyle penicillin 1.5 mega units 6 hourly IV for 7 days
is effective treatment11 A3• In patients with penicillin allergy, a program of
erythromycin can be used at 250mg QID for five days. In mild to moderate
cases oral medication using amoxycillin, erythromycin, doxycycline or
ampicillin can be used, subject to contraindications and age limits.
Amoxycillin/ampicilin is useful in case of pregnant women. Co-trimoxazole
is preferred in children. Cap. Doxycycline 100 mg BD daily for 7 days is
effective when given within 3 days of onset of leptospirosis 12 Typical
dosage for doxycycline is 1 OOmg BID for ten days. 3G cephalosporins
( cefotaxime, etc.) are known to be somewhat effective but the primary
drug of choice is always penicillin44 Leptospires are usually resistant to
vancomycin, chloramphenicol, rifampicin and metronidazole. Multiple
antibiotic therapy is not required. Prophylaxis with cap. Doxycycline 200
mg weekly for 6 weeks can be given to agriculture workers during high
transmission season4 .
50
Treatment for complications
Peritoneal or haemodialysis for renal failure, platelet replacement for
thrombocytopenia, blood transfusion in haematological complication and
ventilators in pulmonary involvements are useful measures.
Supportive care
Fluid and electrolyte balance need to be maintained. ECG monitoring is
also important as cardiac arrhythmia~ are common. Psychological
manifestations are common, and patients may require sedation if they
become aggressive or psychotic. These symptoms are temporary and
would not normally require specific treatment, however longer-term
depression, fatigue and other symptoms. Follow up of cases treated is
useful for knowing late sequelae
Risk factors of leptospirosis
Leptospira, the causative organs are maintained in nature by animal hosts
such as cattle, pig, dog, cat, mongoose, wild animals and laboratory
animals. The rodents such as rats, squirrel are also carriers of
leptospirosis. The animals shed Leptospires through urine. They survive
in the environment for long period of time. The environment contaminated
with leptospires is also source of infection. Hence, contact with animals,
animal tissue, animal urine, wet environment, occupational and
recreational exposure to contaminated water bodies are risk factors for
leptospirosis.
Animal reservoir
51
Leptospirosis in animals as a veterin9ry problem and a possible source of
infection to human beings was identified in late 1930s and 1940s2
Waitkins SA reported in 1987 that the transmission cycle of leptospirosis
involves the carrier hosts, the environment and human beings. Most of
rodent and mam111a1 can be carrier and excretes leptospires2
"Leptospiral carrier state and seroprevalence among animal population
a cross-sectional sample survey in Andaman and Nicobar Islands" A total
of 494 sera samples from different domestic animals and 85 samples from
rats (Rattus rattus) were tested by microscopic agglutination test using
nine serogroups prevalent in these islands. Antibodies to leptospires were
detected in 164 samples giving an overall seroprevalence of (33.11 %).
The seroprevalence was highest among cows (40.32%). Of 85 rat (Rattus
rattus) samples tested for antileptospiral antibodies six (7.1 %) were
positive. The two isolates from rats were found to be pathogenic,
belonging to serogroup Grippotyphosa 16. Leptospiral infection among .,
cattle was first recorded in Russia2• Cattle all over the world may be
infected with serovars Hardjobovis,Pomona, and Grippotyphosa. Infection
with lcterohaemorrhagiae, Bratislava, Hebomedis, Autumnalis, Australis,
Sejroe, Canicola and Bataviae also occurs 1• Leptospirosis in cattle could
be totally unapparent or may result in acute febrile illness or severe
complications. W.A. Ellis and colleagues studied leptospirosis in cattle in
Northern Ireland. ln.a study on aborted bovine foetuses Ellis WA eta/,
1978 identified 6.9% leptospiral antibodies in the aborted foetuses,
whereas none of the 196 non-aborted foetuses had antibodies. The study
provided clue for trans-placental transmission of leptospirosis in cattle.
52
Certain serotypes are associated with some animal species. Several
studies on cattle leptospirosis were conducted in other countries such as
Spain and Australia also. Alonso-Andicoberry C et a/ (2001) studied 762
diary cattle in Spain. He used microagglutination test (MAT) with 11
leptospiral serovars as antigens. 8% of the cattle showed antibodies.
A study in Andaman and Nicobar Districts showed seropositivity in 40%
of the cows and 26% of the bulls 16. Ratnam S eta/ screened 40 cows in a
village near Chennai. Antibodies against leptospires were found in 68% of
the cows. A survey by Sehgal SC et al, in villages affected by an outbreak
of leptospirosis in Thane in India in 2001 showed a similar seroprevalence
among cattle.
Other animals that are carrier of leptospirosis are pigs, sheep, dog, cat.
Canicola and lcterohaemorrhagiae are the common serovars that infect
dogs2. Scanziani E et a/ conducted a serosurvey in 2002 among 245
. kennelled dogs in Italy, 72 were found to be seropositive. Venkataraman
KS & Nedunchelliyan S (1992) reported an outbreak of leptospirosis in
human beings and dogs in Madras City. Following the outbreak, a
serosurvey was conducted among humans and dogs. Seroprevalence
was 50.5% among humans and 21.3% in dogs. Leptospira belonging to
serovar lcterohaemorrhagiae was isolated from a human patient and
Canicola from a dog.
Wild animals and labpratory animals are also affected by leptospirosis
(Ruiz-Pina HA et a/ (2002). Seroprevalence rate of 38.2% was found in
sea lions in California by Colagross-Schouten AM eta/ (2002).
53
Smythe LD et a/ (2002) studied Australian flying foxes (bats) in
Queensland and found 28% seropositivity. Bunnell JE et a/ (2000)
conducted a study among wild mammals in Peruvian Amazon basin.
Seroprevalence was 39% in the opossums and 35% in bats (35%) The
study indicated that wild mammals could be more important reservoirs of
leptospires.
Rodents
The role of rodents in the transmission of leptospirosis was understood
after the discovery of leptospires as the cause of Weil's disease. Rodents
are the first recognized carriers of leptospires. They are source of
infection to human beings. lcterohaemorrhagiae serovar is associatea
with rodents and other serovars have also been isolated. Various studies
done in different countries provided evidence for it. A study by Matthias
MA & Levett PN (2002) estimated seroprevalence rates of 28.2% and
40.7% in mouse and mongoose respectively in Barbados. Leptospires
were isolated from mouse. A test to detect anti-leptospiral antibodies in
mammals was developed by modifying the lepta-dipstick test as reported Q
0
by Gussenhoven GC eta/, 1997. Eighteen of the 60 (30%) wild rodents
were positive in the test in a study by Kollars TM Jr eta/ in 2002. Alder H
eta/ (2002) studied rodents and shrews in Zurich, Switzerland for knowing
leptospiral carrier rate. They sreened 190 Kidney specimens from small
animals by polymerqse chain reaction (PCR) and 12.6% were positive. In
another study in Turkey conducted in Rattus norvegicus rodents showed
27.1% positivity in the kidney samples and 16.9% of brain samples
(Sunbul M et a/, 2001 ). Saravanan R et a/ (2000) studied 28 rats and 58
54
bandicoots at Avadi, Chennai, India Anti-leptospiral antibodies were seen in
14.3% of the rats and 16.1% of the bandicoots. Natarajaseenivasan K et a/
(2003) studied field rodents near the rice mills of Salem, Tamil Nadu, India
following leptospirosis in rice mill worker. A study in Andaman Island
seroprevalence rate among rats was found 52.1%16 . We reviewed the following )
studies for risk factors.
Table1. Studies on risk factors of leptospirosis reviewed.
Authors Bovet Pet a/
Study title Risk factors associated with clinical leptospirosis: a population-based case control study in the Seychelles (Indian Ocean) Seychelles District
Place Seychelles (Indian Ocean)
Year 1999
Tangkanakul Risk factors associated with North eastern 2000 W eta/ leptospirosis 'ln North-eastern Thailand
Thailand, 1998
Sugunan AP Risk factors of leptospirosis in Andaman Andaman Island- A matched Island, India case control study
2002
Risk factors associated with leptospirosis in North-eastern Thailand, 1998.
A case-control study was conducted in Nakhornratchasrima Province in
the Northeastern region of Thailand in 1998 by Waraluk Tangkanukul, Piyanit et
al with the objective to identify risk factors leptospirosis on admission which could
be useful for early diagnosis and treatment in Thailand. The study was conducted
between August and December, 1998. For this study, a suspect case was
defined as a resident of Nakornratchasrima Province greater than .15 years old
who presented to the community or provincial hospitals between August 22 and
55
December 31, 1998 with fever, headache, and myalgias. A confirmed
case was defined as a suspect case with a positive test result for anti-
0 leptospiral positive lgM antibody using the Panbio enzyme-linked
immunosorbent a_ssay (ELISA) (Panbio, Inc, Brisbane, Australia).
Two persons from the neighborhood of the cases who did not have any
illness during the previous 30 days and found negative in lgM ELISA test
were selected, after matching to the corresponding case for age (+l-5
years) and sex, as controls. Total 59 cases and 118 controls were
included in the study. A standardized questionnaire was used to collect
information from the study participants on activities associated with water
and animals and environmental conditions of house and workplace. An
environmental survey was also conducted at the house and workplace.
During the study period 62 cases of the 80 suspects identified from
Nakhornratchasrima Province were confirmed by lgM ELISA. Three
patients died that were excluded from the study. Among the remaining 59
cases, 51 cases had two controls matched for age-sex. Remaining 8
cases had one control. each. Univariate matched analysis suggested that
activities in wet fields for more than 6 hours per day (ploughing, pulling
out sprouts, replanting sprouts and fertilizing), walking through water,
having cuts on feet in the 2 weeks before were significantly associated
with leptospirosis. Keeping dog was protective. Sowing, fishing and not
wearing boots wer.e not significantly associated. The authors did
multivariate conditional logistic regression analysis. The adjusted odds
ratio indicated that walking through water in two weeks prior to illness was
found associated. Pulling out sprouts, plowed and fertilizing in wet fields
56
for more than 6 h/day were significant independent variables associated
with leptospirosis.
lgM ELISA used to diagnose or exclude asymptomatic controls has
sensitivity and specificity of about 93%. Hence, false positive and
negative tests would result in some differential misclassification leading
to altered estimation of the strength of association. 77.5% positivity in lgM
ELISA test inspite of a liberal case definition used is matter of
" consideration. The test can detect lgM antibodies upto about three
months of infection. Infection in controls prior to three months can not be
detected. This would result in misclassification. The study might have
failed to identify risk factors of other seasonal activities as the study was
done during August to December. The exclusion of died cases severe
" cases would result in an under-estimation of the strength of association.
The identified risk factors are modifiable. Behavior change communication
in agriculture workers by awareness campaign and adoption of newer
techniques of cultivation are important measures to address the disease.
Risk factors associated with clinical leptospirosis: a population·
based case-control study in the Seychelles (Indian Ocean).
This study was conducted in Seychelles Islands by Pascal Bovet, Claude
Yersin et al from 1 April 1995 to 31st March,1996. The objectives were to
determine the inciqence of acute leptospirosis, the prevalence of
subclinical infection in the healthy population and to identify risk factors of
acute leptospirosis in an endemic tropical setting. In previous study high
incidence of leptospirosis (40- 60/100,000) was found in Seychelles.
57
The study was conducted in two big hospitals of the country having facility
of treatment. All the physicians of the country were informed to refer
patients of suspected leptospirosis to these hospitals. Suspects who had
seroconversion (to a minimum titre of 1 :400) or four-fold rise in titre in
microagglutination test (MAT) or had a positive result in PCR assay were
considered as cases. Eligible controls were selected from a list of 1 067
subjects aged 25-64 randomly selected from census data and who had
participated in other study in past. For each case-patient, age, sex and
occupation matched persons were selected from the list. Those controls
scrsened by MAT and PCR and found negative were considered as
definite control for the case. Controls were matched for time· period by
selecting and investigating them within 15 days of identification of case,
Information about demographic, social, educational, occupational,
environmental and behavioral variables was obtained using a
questionnaire in interviews of cases and controls. In the study 75 of the
125 identified suspects met the laboratory criteria for a definite diagnosis.
Among 125 controls identified, 60 were positive in either MAT or PCR.
Hence they were excluded. Of these 75 cases and 65 controls, 38 were
original matched pairs.
The authors did univariate conditional and unconditional regression
analysis. 1 0 and 15 variables were found statistically significant,
respectively. Multiv~riate backward logistic regression indicated that the
strongest independent correlates of acute leptospirosis were, by
decreasing odds ratios, gardening, cats at home, skin wound, drinking
home brews, wet soil around home, refuse not being collected by public
58
service, home built of corrugated iron and inversely indoor occupation.
Combination of gardening, skin wound and wet soil around home
accounted for 37 % variance in predicting acute leptospirosis.
The paired MAT and PCR are highly sensitive and specific standard tests.
The tests were used to confirm cases and exclude leptospirosis in
controls. Hence the chances of misclassification are minimal. The
incidence of leptospirosis calculated (101/100,000) was higher than the
previously reported annual inciden9e in Seychelles. This indicates better
sensitivity than that in the routine surveillance system.
The study period was one year covering all seasons. Hence seasonal
exposure factors are taken care of. Due to large sampling frame of
controls identifying of matched controls for all cases was possible to get
better outcome. Moreover, it was not proper to do an unmatched analysis
on partially matched pairs. There is no clarity regarding multivariate
logistic regression model whether it was conditional or not.
The modifiable risk factors identified in the study are drinking home
brews, skin wounds, house refuse and gardening. A control programme
can address these issues. People can be made aware of the risk factors
and encouraged to protect them by wearing footwear and protective
clothing during gardening or walking on wet lands. Treatment of skin
wounds can reduce the risk of leptospirosis.
Risk factors of leptospirosis in Andaman Islands- A matched case
control study.
59
A.P. Sugunan conducted this matched case control study as a part of
MAE-FETP study. The objective of the study was to identify potentially
modifiable independent risk factors associated with acute leptospirosis in
Andaman Islands. The study was conducted in Rangat 'and adjoining
villages in Middle Andaman, Andaman & Nicobar Islands during October-
November, 2002. A suspected case of leptospirosis in Rangat was
defined as any patient who reported to CHC, Rangat on or after 1 October
2002 with complaints of fever associated with any of the following 0
>
symptom/signs (a) Severe muscle tenderness (b) Any bleeding
tendencies including sub-conjunctival haemorrhage (c) Jaundice (d)
Cough, haemoptysis and breathlessness (e) Oliguria (f) Signs of
meningeal irritation. A confirmed case was defined as a suspect who 0
showed serological evidence of current leptospiral infection
A set of eligible controls for each case was selected from the
neighborhood of the cases matching for age (=< 5 years) and sex. The
selected persons were screened for serological evidence of asymptomatic
or past leptospiral infection. Two seronegative persons were selected for
each case as controls. A blood sample was collected from the suspected
cases during the acute phase and another sample 10 - 14 days later.
One blood sample was collected from all the eligible controls.
Information about potential risk factors was obtained by
interviewing the cas~s and controls using a structured questionnaire and
observation. The information included type of house, house surroundings,
proximity to water bodies, ownership of house and agricultural land,
contact with animals, participation in agricultural activities, fishing, contact
60
with garbage and sewage, cleaning animals, direct contact with animal
urine, and recreational activities such as swimming.
information about such exposure was considered during a four week
period prior to onset of symptoms in the case of cases and during the •
corresponding period for their matched controls.
Total114 suspected cases of leptospirosis were admitted in Rangat CHC.
79 paired blood samples were tested 38 showed seroconversion and 17
had four fold rise in paired titre. Diagnosis was confirmed in 58 cases. The
case fatality wa~ 9.4%.
Thatched roof, use of stream water for drinking and keeping cattle and
pigs in house were significantly associated with leptospirosis. Among
occupational and behavioral factors, walking barefoot, having wounds,
harvesting, cleaning sewage, clearing garbage were significantly 0
associated working standing in water. The strength of association was
highest for keeping cattle in house (OR: 5.63) followed by harvesting (OR:
5.43) and using well water for drinking (OR: 5.0). Having goats, cats and
dogs in house, rat infestation of houses, fresh water fishing, swimming in
$,treams and having direct contact with animal urine were not found to be
significantly associated with acute leptospirosis.
The author did multiple logistic regression with backward elimination
process. Five variables remained in the model. Presence of cattle in the
house had the strongest association with leptospirosis (OR: 5.1) followed
by use of streams as a source of drinking water. Cleared garbage, walks
barefoot, worked standing in water were other significant factors.
61
The author followed standard procedures sampling and laboratory
• methods. The analysis is acceptable one. The author had excluded six
fatal cases due to non availability of results. It could have resulted in
underestimation of strength of association. The author did not estimate
various gradations of exposures.
Prevention and control
Prevention of leptospirosis essentially ·is by identifying the source and
interrupting the transmission 1. The large number of serovars and of
infection sources and the wide difference in transmission conditions make
leptospirosis difficult to prevent. Preventive measures should be based on
knowledge of those groups at higher risk of infection and of local
epidemiological factors; they includ~: Identifying · and controlling the
source of infection (e.g. open sewers, contaminated wells) .. Control of
feral reservoirs is often not feasible but control measures can be highly
effective in small, defined area3.4·6. Selective rodent control may be
important. For interrupting transmission, thereby preventing infection or
disease in the human host, the following steps are important:
1. Wearing protective clothes and equipment;
2. Disinfecting contaminated surfaces such as stable and abattoir floors;
3. Marking areas with increased risk exposure (warning signs).
4. Preventing infection or disease in human hosts:
5. antibiotic prophylaxis of exposed persons in areas of high exposures
may be effective, e.g. soldiers (doxycycline 200mg in one weekly dose);
6. Raising awareness of the disease and its modes of transmission.
62
0
Epidemics and management:
Conditions leading to an increase of contaminated surface water or soil,
such as rain, floods and disasters increase the risk of leptospirosis and
may lead to epidemics. During periods of drought both humans and
animal reservoirs may be attracted to spare water places, hence
increasing the risk of infection .. Social and recreational activities that
expose persons to a contaminated environment increases also the risk.
Early diagnose and prompt treatment is the key of control. Rapid
diagnostic screening tests are useful for early diagnosis. Identification of
the serovar and the source is important for appropriate measures. Attack
rate and seropositivity amongst populations over a time period are useful
indicators of control. Infection source and transmission conditions should
be identified. Animal serology may give information on serogroup status.
Isolation followed by typing gives definite information on serovar.
In different epidemiological setting, different animal species could be the .. ,
primary source of infection. In the case-control study conducted in
Seychelles 10 cats were found to be associated. Sarkar U et a/, 2002
reported that rats were found to be associated with leptospirosis in Brazil.
Animals were associated with leptospiral seropositivity in Andaman
Islands 16 Murhekar MV et a/, 1998 reported cattle associated with
leptospirosis. Significant carrier state in animals could be potential source
of infection to humans, although seropositivity is not a reliable indicator of
carrier state (Ellis WA eta/, 1981 ). Excretion of leptospires in the urine by
bacteriological or molecular tools can be conclusive evidence.
63
Measures targeting human beings include vaccination and
chemoprophylaxis. Vaccines have been developed for use in man {Torten
M et a/, 1973), however the existence of a large number of serovars of
leptospiras makes it difficult to develop a universally effective vaccine.
Chemoprophylaxis with doxycycline was tried in soldiers from non-
endemic areas visiting endemic area~. and was almost 100% effective
{Takafuji ET eta/, 1984). However, Sehgal SC eta/, 2000 found it only
54% protective in a study conducted in endemic area during an outbreak.
Chemoprophylaxis can only be used in outbreak situations or in travelers.
Cap. Doxycycline 100 mg BD for 7 days can be given within 3 days of
onset of symptoms 12•
Developing policy, protocol and programme for prevention and control
measures is important for success of measures. Adequate resource of '
manpower, materials and fund should be ensured at local level.
Interdepartmental co-ordination of health, veterinary and agriculture
experts is essential for the control and manag~ment. Environment
sanitation campaign like "Nirmal Gujarat campaign" can help a lot. For
reducing reservoir of infection antirodent activities in high risk area can be
considered judiciously. Minor engineering works in housing can reduce
exposures to risk factor in rainy season. Prevention and treatment of cut-
wounds, house compound wet are modifiable risk factors and need to be
addressed. Creating awareness by health education by specific IEC is
basic tool for prevention. Capacity building by training of health, medical,
. veterinary, agriculture staff is useful for case detection, referral and
treatment. Early case detection by active surveillance, prompt referral and
64
0
treatment can be life saving. Public private partnership, community
participation and political commitment are essential requirement of
leptospirosis prevention and control. Resource allocation in time should
be ensured. The authority need to identify research needs of local area
and can make provision and motivation for it.
Summary
Leptospires are widespread pathogens and have a large number of
animal hosts. Human infection results from accidental interaction of
people with carrier animals or environment contaminated with leptospires.
Although the basic principles of prevention such as reduction of source,
environmental sanitation, more hygienic work-related and personal
practices etc, are same everywhere, there is no universal control method
applicable to all epidemiological settings. A good understanding of the
ecological, epidemiological and cultural characteristics of a community
that faces the problem of leptospirosis is the essential prerequisite for
evolving an effective and acceptable control measure
65
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